1. Field of Invention
The present invention relates to a farrier's tool. More specifically, but not by way of limitation, this invention is for use by farriers and horse owners to assess the balance of the equine hoof and the alignment of the hoof with the adjoining limb. This invention is a guidance tool that teaches and demonstrates proper hoof balance and alignment. It provides a mechanism whereby horse owners and farriers can care for their horses better and more effectively by providing a unique top/down assessment technique for balancing and aligning the hoof capsule. Additionally, this invention will help both the farrier and horse owner to evaluate the work being done and the effects of changes that are made to the hoof capsule in order to correct pre-existing imbalances and hoof-to-limb misalignments.
The following patents granted appear to be related to the current invention but do not specifically apply or cannot be utilized in the manner in which the current invention is used:
U.S. Pat. No. 4,214,370 (Beaston) discloses a hoof alignment tool capable of wrapping around a hoof for measuring, see FIG. 3.
U.S. Pat. No. 7,165,623 (Healey) discloses a general farrier's measuring tool for determining a break-over point and preparing a hoof for shoeing, see column 1, lines 7-24.
The following documents appear to disclose structures that involve a wraparound feature for use on a hoof (not necessarily a horse), however none of these documents appear to disclose any use or involvement of estimating hoof alignment or related hoof geometrical measurements.
DE202005004464 (Drucker) discloses a wraparound structure for use on a hoof, see the front page drawing.
USPA 2007/0033909 (Lustgarten) discloses a custom made boot and shoe for hoofs in which a plastic material is heated to softening, thereby allowing it to be wrapped around the hoof; see FIGS. 3 and 8A/B for “split-ring” type structure. Also see USPA 2003/0167739 (Clark et al.).WO2004/017729 (Nolan) discloses farrier's shoeing appliance, including a partial wraparound structure which is attached to the hoof, see front page figure.EP860115 (Lieby) discloses a device to protect the hoof of a horse including a wraparound structure, see FIG. 7. Also, see GB2432293 (Pickering).
GB1463211 (Ensinozo) discloses a hoof protector that wraps around the hoof, see FIG. 1.
The remaining cited documents show various hoof attached devices that could be usable in aligning a hoof or determining misalignment, but which appear to be silent regarding disclosure of actually applying of this feature.
List of Uncovered Documents
US Patents:
U.S. Pat. No.Issue Date (M/D/Y)InventorAssignee7,065,62301/23/2007Healeyn/a4,214,37007/29/1980Beastonn/a3,682,17908/08/1972Firth et aln/a1,116,32611/03/1914Powlowski et aln/a  619,36102/14/1899Stephensn/aUS Patent Application Publications:
Publication No.Issue date (M/D/Y)InventorAssignee2007003390902/15/2007Lustgartenn/a2003016773909/11/2003Clark et al.n/aForeign Patents:
Publication dateDocument number(M/D/Y)InventorApplicantWO2004/01772903/04/2004NolanNolanWO0301550902/27/2003MustadMustad et alEP086011508/26/1998LiebyLiebyGB243229305/23/2007PickeringPickeringGB146321102/02/1977EnsinozoEnsinozoDE10200501518310/05/2006HoffmannHoffmannDE20200500446406/30/2005DruckerDE1982609911/19/1998BrosigBrosigJP8-21475208/27/1996SanoNaru ToreidenguJP4-02732401/30/1992NaraharaNarahara
2. Prior Art
The equine hoof is a complex structure. Internally, it is composed of a bony column including digital phalanges and distal sesamoid bones, tendons and ligaments, and an extensive nail bed that is profoundly vascular. External structures include the area of joinder between skin and horny outer shell, the coronet band, the horny material that is the hoof proper, and a ground surface which includes the sole, the frog, and the bulbs of the foot.
While one might easily think of the hoof as a wooden, static structure, which once grown does not change. The hoof is, in fact, plastic and fluid in its response to impact pressure. Functionally, the equine foot in conjunction with the adjoining limb must at any given moment absorb tremendous concussion as the horse moves about. In order to effectively absorb many tons of impact pressure, the hoof structures must be both supple, which attenuates the impact of concussion, and fluid, which attenuates the hard slap of footfall against a hard surface. One might think of the equine foot as hydraulic in nature.
The hoof capsule deforms each time it accepts the load of movement. This deformation is one of expansion and contraction, made possible by the broken circle of the hoof capsule, the fluidic nature of the internal structures, and the suppleness of the column of bone and ligament within the foot. Once the impact wave has dissipated, the hoof capsule rebounds to its original shape and the bony column regains its resting posture. The foot is ready once again to absorb the next impact. In this way the equine foot and leg act as living shock absorbers.
Clearly, the unprotected equine hoof will wear and degrade with activities of daily life. Nature has provided for this eventuality by constantly replenishing the horny material that is being worn away or degraded. Like the human fingernail, the hoof capsule, the container for all internal structures, originates from a keratogenous membrane. This horn-producing substrate replenishes the hoof throughout the horse's life. In the wild, hoof growth commonly equals the rate of degradation and wear caused by daily foraging and self-preservation. In captivity, given the increased stress of riding the horse, the degradation of the hoof capsule is often greater than the rate at which it can be replenished by the nail bed. For this reason, the horseshoe was invented.
Once affixed to the hoof, the horseshoe effectively stops all degradation of the horny hoof. Absent degradation, some artificial treatment of the hoof is required to maintain the structure's integrity and functionality. Most often, a farrier is summoned to trim the excess growth and reapply the protective shoe. In shoeing the horse, the farrier must make choices about how best to attain the optimal shape, length, and angle of the hoof.
There is universal agreement in the horse community that some combination of angles, distances, thicknesses, or other measures of the hoof affect the motion, comfort, and soundness of the horse. Historically, farriers, veterinarians, and horsemen have discussed and promoted techniques for trimming and shoeing the horse that they believed to be the best ways to preserve its comfort and soundness. Yet, as evident from the ongoing debate, the practice and theory of the proper trim and balance of the equine hoof has remained a point on which there is no consensus.
However, one theorem is certain: In order to change the balance and alignment of the equine foot and limb, one must change the way the hoof strikes the ground. This is accomplished by leaving or removing portions of the ground surface of the hoof capsule.
The farrier's responsibility is to interpret the equine foot and determine how much material should be removed from a particular aspect of the hoof capsule in order to assure the most beneficial balance for the horse. The hoof capsule, however, because it is constantly growing, is constantly changing. As the hoof capsule changes, the distribution of impact forces through the equine foot and limb also changes. Correctly removing portions of the ground surface of the hoof capsule allows the hoof to address the ground in a way that benefits and preserves the horse's comfort and soundness.
Traditional understanding teaches that one must evaluate the balance of the hoof capsule at the instant of touchdown at the end of stride. If the hoof capsule meets the horizontal plane flat, with the possible exception that the heels might strike the surface slightly before the rest of the foot, it is considered to be balanced. Conversely, if one side of the hoof capsule touches slightly ahead of the other, it is imbalanced. The side of the hoof capsule that touches first must be reduced only enough to allow the hoof to again contact the horizontal plane flat. The question then becomes, how much is enough? Given this traditional viewpoint, one can easily understand why farriers have focused almost exclusively on the bottom of the horse's foot to find its balance. This focus is further evident in past patents claiming balancing the equine hoof as inherent in the invention.
While balancing the equine hoof capsule using the instant of contact as the primary variable is logical, it is clinically impractical. Not only is instant of contact too fast to analyze by simple observation, but also there are few locations at which a horizontal surface is available on which to observe the horse in motion. Additionally, should such a surface be available, there is the additional problem of the influence of the person leading the horse on the movement of that horse.
One must look for evidence of balance that can be analyzed and studied over time. This evidence would ideally be more substantial and permanent, allowing for measurement. In fact, such evidence is found in the deformation of the equine hoof capsule. This deformation might be thought of as an average of all the forces acting on the hoof by the adjoining limb, concussion from movement, and static pressures created by the mass of the horse.
If the hoof capsule is perfectly balanced, it will not deform. A perfectly balanced hoof is a theoretical concept, like a vacuum. In reality, all hoof capsules are in some state of deformation, no matter how slight. Fortunately, the hoof capsule deforms predictably in response to known conditions of the hoof wall. Learning to correct imbalances by interpreting hoof capsule deformations takes years of practice. Even with experience, one may misinterpret the deformation and fail to correct the problem.
Horse owners must rely upon the expertise of their farriers. So long as their horses remain sound and comfortable, they must assume that the work being done on their horses is correct. They do not know their horses are getting inappropriate care until they are prematurely lame. Until and unless some method of checking the work being done by farriers is devised, this unfortunate circumstance will continue to affect a growing number of horses and their owners.
In recent history, the horseshoeing trade has suffered a breakdown in its once effective and demanding system of education, the apprenticeship system. In the past, an apprentice spent years honing and mastering his skills under the tutelage of a Master Farrier/Blacksmith. Long after the Apprentice had graduated from the ranks of apprenticeship to the coveted level of Journeyman, he was expected to continue his education with the shop Masters. Only after many years of toil would the apprentice finally rise to the rank of Master Farrier. Not until then would he have gained adequate knowledge to venture into his own shop and business. Though a worthy system, it was born of a less hectic era and although still a respected educational model, it has been largely forsaken.
To fill the void created by the breakdown of the apprenticeship system, master farriers formed Shoeing Schools. While such institutions are certainly effective in introducing the basic mechanics of shoeing, they are typically short courses and, therefore, cannot be expected to teach the fine techniques of the Art of Shoeing in the limited time available for classroom pedagogy and practical application. Because of this unhappy solution for the anachronistic Apprenticeship System, the Art of Farriery is vanishing and along with it, the reliable quality of the farriers' craftsmanship. Unfortunately, it is the horse who is most affected by this unfortunate turn of events. For it is the horse whose comfort and soundness is at risk when his therapy is the responsibility of an insufficiently experienced or educated craftsman.